The present invention is directed to bonding processes and, in particular, to monitoring a condition of a surface during a preparation stage of a bonding process.
Structural bonding of composites is currently being pursued as a replacement for conventional fasteners in assembly of aircraft and aircraft components. During a structural bonding process, surface preparation is performed to ensure that the bonding surfaces are free from oxides and are therefore receptive to adhesive materials. One method of surface preparation uses plasma discharge to atomically cleanse a bonding surface of oxygen. However, it is necessary to determine that the plasma discharge has sufficiently cleansed the bonding surface of oxygen prior to performing a structural bonding step.
Accordingly, it is desirable to inspect the surface to determine whether or not the surface has been sufficiently conditioned by plasma exposure before bonding.